Apparatus for perforating sub-sea well bores

ABSTRACT

In the representative embodiment of the present invention disclosed herein, a new and improved perforating gun includes a plurality of relatively-short metal strips respectively carrying one or more encapsulated shaped explosive charges and which are tandemly intercoupled by unique couplings cooperatively arranged so that the strips can pivot freely about two perpendicular transverse axes but with little or no rotation or twisting of the strips about the longitudinal axis of the gun assembly. In this manner, the gun assembly can be readily dispatched through multicurved flow lines to selected remotely-situated sub-sea well bores and halted in a predetermined position with assurance that the several shaped charges will be oriented in a predetermined angular direction. The gun assembly may also include one or more tandemly-coupled tubular members which are connected between the gun positioner and the uppermost strip as required for locating the shaped charges at a predetermined distance below the positioner. These tubular members are cooperatively arranged for temporarily bending as the gun assembly is dispatched to a subsea well bore while still retaining the strips in a selected angular orientation relative to the gun positioner.

United States Patent 91 Dermott [451 Feb. 11, 1975 APPARATUS FORPERFORATING SUB-SEA [73] Assignee: Schlumberger Technology Corporation,New York. N.Y.

221 Filed: Mar. 25, 1974 211 Appl. No.: 454,495

[52] U.S. Cl 175/451, 175/453, 403/162 [51] Int. Cl. E211) 43/117 [58]Field of Search l75/4.5l, 4.53, 4.6; 166/551; 403/161, 162, 111; 102/20;89/] [56] References Cited UNITED STATES PATENTS 2,540,319 2/1951 Bitzer403/161 2,799,224 7/1957 Long 175/46 X 2,960,930 ll/l960 Bell 175/4533,100,443 8/1963 Pohoriles i 175/453 X 3,177,808 4/1965 Owen 102/203,282,213 ll/l966 Bell et al l75/4.6 X 3,465,836 9/1969 Fields 175/4.5l

FOREIGN PATENTS OR APPLICATIONS 143,322 4/1961 U.S.S.R 175/453 PrimaryExaminer-David H. Brown Attorney, Agent, or Firm-Ernest R. Archambeau,Jr.;

William R. Sherman; Stewart F. Moore [57] ABSTRACT In the representativeembodiment of the present invention disclosed herein, a new and improvedperforating gun includes a plurality of relatively-short metal stripsrespectively carrying one or more encapsulated shaped explosive chargesand which are tandemly intercoupled by unique couplings cooperativelyarranged so that the strips can pivot freely about two perpendiculartransverse axes but with little or no rotation or twisting of the stripsabout the longitudinal axis of the gun assembly. In this manner, the gunassembly can be readily dispatched through multicurved flow lines toselected remotely-situated sub-sea well bores and halted in apredetermined position with assurance that the several shaped chargeswill be oriented in a predetermined angular direction. The gun assemblymay also include one or more tandemlycoupled tubular members which areconnected between the gun positioner and the uppermost strip as requiredfor locating the shaped charges at a predetermined distance below thepositioner. These tubular members are cooperatively arranged fortemporarily bending as the gun assembly is dispatched to a sub-sea wellbore while still retaining the strips in a selected angular orientationrelative to the gun positioner.

19 Claims, 5 Drawing Figures APPARATUS FOR PERFORATING SUB-SEA WELLBORES Many proposals have, of course, been advanced heretofore forproducing oil and gas from sub-sea wells. Typically, a number of thesesub-sea wells are drilled at spaced intervals about a central surfaceplatform to minimize drilling costs as well as to later simplify thecollection of oil or gas from the wells. To facilitate the performanceof various completion operations, generally-horizontal production linesare usually laid along the ocean floor from this central platform andrespectively terminated in a large-radius reverse bend or nearlycircular upright loop of tubing arranged on each wellhead for providingaccess to the usually-vertical production string in the well bore. Asdescribed more completely in U.S. Pat. No. 3,419,694, U.S. Pat. No.3,465,836 and U.S. Pat. No. 3,490,280, so-called through-the-flowline orTFL pump-down equipment is preferably employed for conducting thevarious servicing and completion operations which are ordinarily donewith cable-suspended tools where the wellheads are directly accessiblefrom above.

Production systems such as discussed above have geen generallysatisfactory where the sub-sea wells are grouped reasonably close totheir associated production platform. It will be appreciated, however,that a production system for a large number of widelydispersed sub-seawells requires either many small surface platforms at scatteredlocations around the subsea field or only one or two large platformswith a large number of very long production lines. In either case, thereare obviously many economical and ecological disadvantages.

Accordingly, as described in detail in the December, 1970, issue ofWorld Oil, it has recently been proposed to instead conveniently locatea self-contained underwater production unit near each of several groupsof closely-spaced wellheads in a given sub-sea field and use a minimumnumber of common gathering lines for connecting each of theseself-contained units either to a single surface platform or to asuitable nearby gathering station on land. It will, therefore, berecognized that this arrangement will eliminate the necessity of runninglarge numbers of individual production lines between each well and theircentral gathering points. The many advantages of production systems suchas this are, of course, readily apparent to those skilled in the art.

As best illustrated on pages 47 and 48 of the aforementioned World Oilarticle, these self-contained production units include complex pipingand valve manifolds with many closely-spaced bends or elbows which areso compactly distributed that any given production line makes manychanges in both direction and elevation over a relatively-shortdistance. Thus, it will be recognized that when a particular TFL tool isdispatched from the central gathering location into a given sub-seawell, the tool will experience many changes in direction; and most ofthese directional changes will be made in relatively limited spans oftravel which may well be substantially less than the overall length ofthat tool. This, therefore, makes it essential for any TFL completion orservicing tool that is used with these new sub-sea production systems tobe fully flexible or highly articulated throughout its entire length soas to readily negotiate these many turns.

Those skilled in the art will appreciate, of course, that mostcompletion and servicing tools can be generally arranged for providingsufficient flexibility or articulation to enable that tool to besuccessfully used in a underwater production system with theaforementioned self-contained production units. Techniques such as thoseshown in U.S. Pat. No. 3,490,280 will, therefore, be suitable in mostsituations. It will be realized, however, that most servicing andcompletion tools are capable of operating independently of their angularorientation in a production string.

Several particular difficult problems are presented, however, inproviding reliable TFL tools for perforating sub-sea wells which areserved by these selfcontained production units. First of all, it will berecognized that any perforating tool which is to be used in theseproduction systems will necessarily employ a number of tandemly-disposedshaped explosive charges which are respectively enclosed in individualpressuretight capsules. As previously discussed, these shaped chargesmust be movably or loosely intercoupled in such a manner that even anexceptionally-long assembly of these encapsulated charges can safelynegotiate the many turns and restrictions in the production unit and theflowlines extending between the production unit to a given sub-seawellhead and the central gathering point. It is, of course, essentialthat these charge capsules be firmly secured in such a manner that theywill not be dislodged from the perforating assembly as the tool is movedthrough the various turns and obstructions it will encounter.

A simple, completely-flexible interconnection between the several chargecapsules in a given perforating tool will, however, not always be whollysatisfactory. In particular, there are many sub-sea wells with two ormore formation intervals that are individually completed and separatelyconnected to different production strings. Since such sub-sea wellscommonly employ a so-called multiple completion technique, this resultsin a first shorter production string being terminated in the highestproductive interval and at least a second longer production string beingextended through this first interval to a second lower productiveinterval. As a result, it is, of course, essential that perforation ofthis highest productive interval is safely accomplished without damagingor piercing the longer production string. U.S. Pat. No. 3,338,317 showshow such multiple-completion wells are typically arranged; and, fromthat patent, it can be recognized how critical it is to accuratelyorient a perforating gun in these wells. A similar problem will alsoexist even where only one production string is employed in a sub-seawell since the usual practice is to have a parallel string of tubingwhich is used to reverse tools out of the production string. This, ofcourse, means that perforation of the production string must also bedone without hitting the parallel string.

Accordingly, it will be recognized that one ofthe most reliabletechniques for perforating such multiplecompletion wells is to arrangethe perforating tool and the lower end of each production string asgenerally shown in U.S. Pat. No. 3,465,836. As fully described in thatpatent, a landing nipple coupled into the lower portion of the pipestring is provided with a prepositioned indexing groove which is adaptedto receive a complementary locating lug arranged on the perforating toolfor positively orienting its several shaped charges away from anyadjacent tubing strings. The same or a similar arrangement would, ofcourse, be used where there is only a single production string and aparallel return-flow string.

TFL perforating tools such as these have heretofore used various typesof carriers or connectors for intercoupling the shaped charges. Forexample, spaced-wire carriers such as shown in U.S. Pat. No. 3,282,21 3have been successfully used in the older sub-sea production systems.Similarly, various arrangements of interlinked capsules as shown in U.S.Pat. No. 2,799,224 or U.S. Pat. No. 3,100,443 are also entirely suitablefor TFL perforating operations in these earlier types of sub-seaproduction systems.

It must be recognized, however, that all of these previous arrangementsfor intercoupling shaped charges so as to allow limited bending of theoverall carrier were designed specifically for those earlier sub-seacompletion systems which had production lines with only a singlelarge-diameter loop at the wellhead and perhaps a few widely-dispersedgradual bends lying flat along the sea floor. In particular, since theseprevious sub-sea completion systems were deliberately installed so as toavoid any sharp turns, it was sufficient, and even preferred, that a TFLperforating carrier was capable of flexing in only one bending plane orplane of movement at any one time. Arrangements such as this were,moreover, specifically designed so as to greatly minimize, if nottotally eliminate, the capability of these prior-art carriers to eitherbend in another plane of movement of twist about their longitudinal axisso as to be certain that the charges would always remain in theirpredetermined orientations.

It will be recognized, however, that since these recently-proposedself-contained production units have so many closely-spaced sharp bendsand changes of both direction and elevation in short distances, none ofthe perforating tools described in the aforementioned patents are at allcapable of safely negotiating these turns. In fact, as far as is nowknown, only the somewhat-elaborate carrier shown in U.S. Pat. No. 3,!77,808 could possibly be capable of safe operation in production systemsusing these new self-contained sub-sea production units.

Accordingly, it is an object of the present invention toprovide TFLperforating apparatus of a straightforward and inexpensive design whichis capable of safely negotiating many closely-spaced changes indirection and elevation in a sub-sea production piping system such asthat shown in the aforementioned World Oil article.

This and other objects of the present invention are accomplished byarranging new and improved TFL perforating apparatus to include aplurality of relatively-short charge-supporting members which aretandemly intercoupled respectively by upright linking pins looselydisposed in a socket for joining the ends of adjacent charge-supportingmembers to enable these members to pivot freely about the pins in afirst plane of movement as well as to turn freely in a second plane ofmovement which is generally perpendicular to the first movement plane.Significant twisting of the chargesupporting members about the overalllongitudinal axis of the entire assembly is, however, prevented byuniquely arranging the adjacent interengaged surfaces of the adjoiningends to accommodate turning in the first and second planes of movementbut to resist twisting about this axis as well by providing biasingmeans to maintain these adjacent surfaces coengaged.

The novel features of the present invention are set forth withparticularity in the appended claims. The invention, together withfurther objects and advantages thereof, may be best understood by way ofthe following description of exemplary apparatus employing theprinciples of the invention as illustrated in the accompanying drawings,in which:

FIG. 1 shows a preferred embodiment of new and improved perforatingapparatus arranged in accordance with the principles of the presentinvention positioned in a schematically-represented sub-sea well bore ofa typical design;

FIGS. 2 and 3 are enlarged views of a portion of the perforatingapparatus shown in FIG. 1 for illustrating the details of a new andimproved strip-intercoupling arrangement which facilitates the passageof the perforating apparatus through the production conduits extendingbetween the depicted sub-sea well bore and a distant location at thesurface;

FIG. 4 is a cross-sectional view taken along the lines 4-4 in FIG. 2;and

FIG. 5 depicts a preferred embodiment of another portion of the new andimproved perforating apparatus of the present invention.

Turning now to FIG. 1, a preferred embodiment of new and improvedperforating apparatus 10 arranged in accordance with the principles ofthe present invention is illustrated as it will appear within aproduction system 11 which is coupled to a typical sub-sea well bore 12penetrating one or more productive earth for mations, as at 13. As iscommon, a typical casing string 14 which is cemented, as at 15, in placeand extended to a considerable depth in the well bore 12 is supported bya suitable wellhead 16 mounted on the floor 17 of the sea or whateverbody of water is situated thereabove. The production system 17 includesa number of flowlines, as at 18 and 19, which are coupled to valves 20and 21 on the wellhead 16 and laid along the sea floor 17 to a distantunderwater production unit (not shown) such as described in theaforementioned World Oil article. In the example illustrated, two ormore strings of piping, as at 22 and 23, have been suspendedside-by-side in the well bore 12 and extended to a short distance belowthe lower limit of the formation 13. Depending upon the particularoperating requirements for that particular well, it will, of course, beappreciated that packers (not shown) may also be coupled into the pipeor tubing strings 22 and 23 for isolating the formation 13 from otherintervals in the well bore 12 above the formation. Similarly, other pipestrings (not shown) may also be arranged in the well bore 12 as requiredfor obtaining production fluids from other formations penetrated by thewell bore.

In any event, in the representative arrangement of the production system11 illustrated in FIG. 1, the tubing string 22 was installed in the wellbore 12 to serve as the production string and the tubing string 23 wasinstalled to provide a reverse-flow string. As described in theaforementioned World Oil article, when the well bore 12 was beingcompleted for production, a suitable locating or landing nipple 24 of asuitable design was coupled in the production string 22 and positionedat a predetermined distance above the formation 13 to provide a stop forsubsequently halting well completion or servicing tools, such as the newand improved perforating apparatus 10, at a known position and in aselected angular orientation in the production string. Aninterconnecting line, as at 25, was also arranged between the closedlower ends of the pipe strings 22 and 23 so that these tools, such asthe perforating apparatus 10, can be selectively returned to the surfaceby simply flowing fluids into the reverse-flow string, through theinterconnecting line, and back to the surface by way of the productionstring.

it will, of course, be recognized by those skilled in the art that FIG.1 simply illustrates one of several possible commonly-used productionstring arrangements being used or currently under consideration by theindustry for such sub-sea wells. Thus, the well bore 12 could just aswell have been arranged as a multiple-completion well as shown generallyin U.S. Pat. No. 3,338,317 so that one production string and itsreverse-flow line are terminated at a packer set somewhat above theupper limit of a given formation (as is shown in U.S. Pat. No.3,419,694) and another production string and its reverse-flow line areextended on beyond that formation to a second packer set above a deeperformation interval. in that situation, standard landing nipples, such asthe one at 24, would be appropriately arranged in each production stringto allow the lower portions of completion tools, such as the new andimproved perforating apparatus 10, to hang below the open end of thatstring. In either well bore arrangement, it would, of course, be equallyessential that the perforating apparatus comes to rest in a specifiedangular orientation so as to clearly avoid damaging either the adjacentreverse-flow line or the adjacent longer string of production tubing.Since the design of the new and improved perforating apparatus 10 is,however, equally suited for any arrangement of pipe strings in the wellbore 12, the specific details of these various arrangements are of noconsequence for understanding the principles of the present invention.

As illustrated in FIG. 1, the preferred embodiment of the new andimproved perforating apparatus 10 is comprised of a number oftandemly-intercoupled tool units including flow or pressure-responsivetool-transporting or tool-propelling means 26, selectively-operablegunactuating means 27, tool or gun-positioning means 28 and adependently-suspended perforating gun 29. in the depicted embodiment ofthe perforating apparatus 10, the tool-propelling means 26 preferablyinclude a short body 30 around which is mounted one or two sealingmembers or opposed swab cups, as at 31. These sealing members 31 are, ofcourse, suitably sized for providing a bidirectionally-sealing, butslidable, fit with the internal walls of the various pipes, as at 18 and22, in the production system 11 and on the sub-sea production unit (notshown) that the perforating apparatus 10 must pass through as it iscontrollably moved into and out of the well bore 12 in response to theselective application of an increased pressure or fluid flow to thesurface ends of those conduits connected by way of the production unitto the pipe strings 22 and 23. Suitable locomotion units. as at 26, areof course, well known by those skilled in the art and, therefore, needno further description.

The new and improved perforating apparatus 10 further includes thegun-actuating means 27 which are basically comprised of one or two shortpressure-tight housings, as at 32 and 33, tandemly coupled to oneanother by suitable articulated or flexible joints 34, such as thatshown in U.S. Pat. No. 3,216,751, positioned between the locomotion unit26 and the housing 35 of the gun-positioning means 28. The housings 32and 33 are arranged for carrying a self-contained power supply, such asa group of batteries (not shown), and one or more control devices (notshown) for selectively actuating detonating means, such as anelectricallyresponsive detonator 36 on the lower end of a detonatingcord 37 carried on the perforating gun 29, whenever the perforatingapparatus 10 has been landed and is safely positioned in the landingnipple 24.

Although it will be recognized that the gun-actuating means 27 canemploy any number of various control devices such as those described inU.S. Pat. No. 3,465,836, for example, a preferred arrangement of thecontrol system for the perforating apparatus 10 includes aposition-responsive switch (as at 21 in that patent) which is bestarranged on the housing 35 of the gun-positioning means 28 forestablishing an electrical circuit only when the gun-positioning housingis correctly seated in the landing nipple 24. As an added safetyprecaution, it is also preferred that the electrical control system forthe perforating apparatus 10 further include a pressure-responsiveswitch (as at 22 in U.S. Pat. No. 3,465,836) which can be arranged onany one of the housings 32, 33 or 35 for completing an electricaldetonating circuit only when the pressure in the production string 22 isselectively increased to at least,

a predetermined pressure level.

Accordingly, as fully explained in U.S. Pat. No. 3,465,836, byelectrically connecting the positionresponsive switch and thepressure-responsive switch (as respectively shown at 21 and 22" in thatpatent) in series relationship with the detonator 36 and the powersupply in the control housings 32 and 33, it can be reliably assumedthat this detonating circuit for the perforating apparatus 10 will beactuated only when the tool is correctly seated in the landing nipple 24and the pressure in the production string 22 has been deliberatelyraised to a predetermined level such as by selectively operating a pump(not shown) at the surface which is in communication with the productionstring. Alternatively, the pressure-responsive switch could be arrangedto close when the perforating apparatus 10 is at a safe depth in thewell bore 12 (i.e., by the known hydrostatic pressure at that depth) sothat the perforating gun 29 will be actuated when the positionresponsiveswitch later closes. Other common techniques, such as a time-actuatedswitch, can, of course, just as well be used for the detonating circuitso long as some fool-proof arrangement is provided to positively avoidpremature actuation of the perforating apparatus 10 before it isunquestionably seated and correctly oriented in the landing nipple 24.

The principal function of the gun-positioning means 28 is, of course,accomplished by cooperatively arranging the housing 35 (and the landingnipple 24) so that this housing will always come to rest in apredetermined angular position in the landing nipple upon movement ofthe gun-positioning means into the landing nipple. Arrangements such asshown in U.S. Pat. No. 3,465,836, for example, will, of course, beappropriate for achieving the objects of the present invention. Sincethe particular details of the gun-positioning means 28 are not importantfor fully understanding the present invention, it is, of course,necessary only to emphasize the necessity of the housing 35 always beingseated in a predetermined angular position or orientation with respectto the landing nipple 24 whenever the perforating apparatus has come torest on the landing nipple. Once this is accomplished, the housing 35will assuredly be oriented in a predetermined relationship with thereverse flow line 23.

It will, of course, be appreciated from the preceding discussion thatthe perforating gun 29 must be capable of simultaneously passing throughtwo or more shortradius bends which are relatively close to one anotherand lie in perpendicularly-intersecting planes. Accordingly, in thepreferred manner of attaining the objects of the present invention, thenew and improved perforating gun 29 is cooperatively arranged as bestseen in FIGS. 1 and 2 to include a number of short chargesupportingmembers, as at 38 and 39, of a rigid explosion-resistant material andwhich are tandemly intercoupled to one another by biaxially-pivotalcoupling means, as at 40, for respectively interconnecting the adjoiningends of the several charge-supporting members. For reasons which willsubsequently be explained,

' it is preferred to form the charge-supporting members,

as 38 and 39, of flat strips of steel having sufficient thickness toreasonably resist significant twisting or torsion about theirlongitudinal axes. It will, of course, be recognized that the lengths ofthe charge-supporting strips, as at 38 and 39, will be dependent uponthe smallest radius of curvature that the perforating apparatus 10 willbe expected to encounter. Similarly, it will also be recognized that thetotal number of perforations which are to be produced during a givenperforating operation will determine the overall number ofcharge-supporting strips, as at 38 and 39, that the perforating gun 29must include.

Each of the charge-supporting strips, as at 38 and 39, is cooperativelyarranged for carrying one or more encapsulated shaped explosive charges,as at 41 and 42, which are securely mounted on the strips to be certainthat they do not become loosened or detached as the perforatingapparatus 10 is moved from the surface through the sub-sea productionsystem 1 1 and into the proper position in the production string 22 asillustrated in FIG. 1. Since there are, of course, many types of shapedcharges (such as those shown in US. Pat. No. 3,094,930 and U.S. Pat. No.3,268,016) which can be used here, it is unnecessary to elaboratefurther on the details of the charges 41 and 42 except to say that most,if not all, encapsulated shaped charges which are typically employedwith prior-art strip carriers will be suitable for the perforating gun29. Similarly, although the detonating cord 37 can be arranged inseveral different ways on the perforating gun 29, it has been foundparticularly advantageous to secure the cord to the gun, as by clips 43and 44, located conveniently between each of the charges, as at 41 and42, and as well as on each of the coupling means 40 assuring that thecord will positively remain in detonating proximity of each of theseveral shaped charges.

Turning now to FIGS. 2-4, different views are shown of the adjoining endportions of the charge-supporting strips 38 and 39 and a preferredembodiment of the hiaxially-pivotal coupling means 40. As illustratedthere, the new and improved coupling means 40 include the tongue-liketerminal end portions 45 and 46 of the strips 38 and 39, which arerespectively offset, as at 47 and 48, in relation to the major portionsof the strips. In this manner, the mating end surfaces of the endportions 45 and 46 will each lie in a common transverse plane located atleast substantially midway between the forward and rearward surfaces ofthe strips 38 and 39. It will be appreciated, moreover, that this uniquearrangement will be effective for respectively longitudinally aligningthe forward and rearward surfaces of each of the several strips, as at38 and 39, as well as the shaped charges, as at 41 and 42, employed inthe perforating gun 29. This will, therefore, allow the largest-possiblesize of shaped charges, as at 41 and 42, to be used for perforating agiven production string, as at 22, without having to needlessly make aclearance allowance just for the added dimension (i.e., the thickness ofone strip) which otherwise would be required where the end portions 45and 46 of the strips 38 and 39 instead simply overlapped without theoffsets, as at 47 and 48.

The new and improved coupling means 40 further include a single pivot,such as a typical machine bolt 49 and nut 50, that is passed throughenlarged circular holes 51 and 52 respectively formed in the center andnear the end of each of the strip end portions, as at 45 and 46.Particular attention should be given, first of all, to the substantialdiametrical enlargement of the holes 51 and 52 in relation to thediameter of the bolt 49. Moreover, it should also be particularly notedthat instead of snugly clamping the opposed inner surfaces of the endportions 45 and 46 between the head of the bolt 49 and the nut 50, thesecoengaged surfaces are instead yieldably held together by biasing meanssuch as a spring or an enlarged and fairlythick elastomeric grommet 53which is cooperatively interposed between a washer 54 under one end ofthe bolt and the adjacent outer surface of one of the end portions.

As represented by the arrows 55 in FIG. 2, the coupling means 40 will,of course, allow the strips 38 and 39 to. pivot relative to one anotherabout the central axis of the pivot bolt 49 in a first plane ofmovement. By rounding or cutting off the corners of the end portions 45and 46, as at 56 and 57, it will be appreciated that the strips 38 and39 can turn freely through a substantial arc of rotation. The plane ofthis first pivotal movement is, of course, perpendicular to the axis ofthe bolt 49 and parallel to the transverse planes defined by the opposedco-engaged surfaces of the end portions 45 and 46.

The coupling means 40 are, however, cooperatively arranged for alsoallowing the strips 38 and 39 to turn freely in a second plane ofrotational movement which is substantially perpendicular to theabove-described first plane of rotational movement. To achieve thisfurther object of the present invention, it will be noted in FIG. 3 thatthe extreme ends or tips of the end portions 45 and 46 are preferablycurved slightly outwardly, as at 58 and 59, away from the opposed matingsurfaces of the end portions. Thus, in view of the relative en largementof the bolt holes 51 and 52 with respect to the diameter of the bolt 49as well as the resilience of the grommet 43, it will be recognized that,as shown by the arrows 60, the strips 38 and 39 are capable of rollingor turning in a second plane of rotational movement which issubstantially perpendicular to the first plane. It will, of course, beappreciated that the detonating cord 37 is sufficiently flexible that itwill not unduly interfer with these biaxial turning movements of thestrips 38 and 39.

As previously mentioned, it is essential that the several shapedcharges, as at 41 and 42, be positively retained in a position wherethey are all facing in the same lateral direction once the perforatingapparatus 10 has been seated in the landing nipple 24. In other words,the several strips, as at 38 and 39, making up the gun 29 must berespectively prevented from twisting or turning about their longitudinalaxes. Since they are relatively short, the strips 38 and 39 themselveswill be of sufficient stiffness that they will twist little if any.Thus, for any serious twisting of the gun 29 to take place, it wouldhave to occur at the junctions of the several charge-supporting strips,as at 38 and 39, making up the gun 29.

The new and improved coupling means 40 are, however, cooperativelyarranged to at least limit, if not prevent, any undue twisting of theseveral strips 38 and 39 about the overall longitudinal axis of the gun29. To achieve this, it will be appreciated from FIG. 4 that torsionalturning of the end portion 45 in relation to the other end portion 46would, for example, require one longitudinal edge, as at 61, to serve asthe fulcrum as the opposite longitudinal edge, as at 62, is lifted upfrom its normal co-engaged position against the other end portion. Thisunwanted twisting movement, however, prevented by the biasing action ofthe grommet 53. It must also be realized that the biasing actionprovided by the grommet 53 is particularly effective for preventing thisunwanted turning by virtue of the major transverse distance (as at 63 inFIG. 4) between the edge 61 and the bolt 49. Conversely, however, due tothe closeness of the bolt 49 to the rounded ends 58 and 59 of the endportions 45 and 46 (as shown by the minor dimension 64 in FIG. 2), thebiasing action of the grommet 53, at best, imposes only a minimumrestraint against turning of the strips 38 and 39 in their second planeof rotational movement.

Referring again to FIG. 1, it will be recognized that in mostsituations, the formation to be perforated, as at 13, will be at asubstantial distance below the landing nipple 24. Thus, some suitablearrangement must be made to couple the several strips, as at 38 and 39,to the gun-positioning housing 35 so as to correctly position theseveral shaped charges 41 and 42 in relation to the pipe string 23. Forapparent reasons, therefore, it will be realized that the perforatinggun 29 must be cooperatively arranged so that the strips 38 and 39 arereliably held in a predetermined angular alignment with thegun-positioning means 28.

Accordingly, in the preferred embodiment of the new and improvedperforating apparatus 10, the uppermost one of the charge-supportingstrips, as at 38, is coupled to the gun-positioning housing 35 by meansof an appropriate number of elongated extension members, such assmall-diameter tubular mandrels 65 and 66, which are tandemlyintercoupled by suitable couplings, as at 67. As best seen in FIG. 5,each of the tubular mandrels, as at 65 and 66, is comprised of aselected length of small-diameter thin-wall tubing. In one arrangementof the new and improved perforating apparatus 10, it was foundparticularly advantageous to employ commercially-available stainlesssteel tubing of a sufficiently-high yield strength to prevent permanentdeformation in service and having an outside diameter of 7/l6-inch and awall thickness of 0.120-inch. Although these dimensions obviouslyrepresent only a typical situation and are not to be considered aslimiting the scope of the present invention, it will, of course, beappreciated that lengths of tubing of this nature will be readilycapable of momentarily flexing easily as the perforating apparatus 10 isdispatched through the production system 11.

Of particular importance to the success of the present invention, itshould also be noted that the use of a number of relatively-shortmandrels, as at 65 and 66, will allow the perforating apparatus 10 to beprogressively assembled (or disassembled) at the surface andsuccessively moved into (or out of) the surface end of a production linethat is under pressure. Techniques for progressively introducing andremoving extralong well tools into and out of pressured well bores are,of course, well known in the art and need not, therefore, be discussedfurther.

As illustrated in FIG. 5, each of the couplings 67 is comprised of a setof complementally-matched male and female tubular connector bodies 68and 69 which are respectively mounted on the adjacent ends of themandrels 65 and 66 and adapted to be telescopically fitted together. Itwill, of course, be appreciated that each mandrel, as at 66, will have afemale connector body, as at 69, on one end and a male connector body,as at 68, on the other end of the mandrel to facilitate theinterchangeable intercoupling of any number of the mandrels into anassembly of a selected overall length. Since it is essential that theseveral mandrels, as at 65 and 66, remain in a predetermined angularalignment with one another, the connector bodies 68 and 69 arerespectively secured on the ends of the mandrels as by threads 70 and 71and set screws 72 and 73 and cooperatively aligned as by a lateral key74 on one body complementally fitted into a longitudinal slot 75 on theother body.

Since the key 74 and the slot 75 prevent relative rotation between thebodies 68 and 69, it is preferred to counterbore and internally threadthe mouth of the female connector body ahead of the key for threadedlyreceiving an externally-threaded coupling sleeve 76 which is looselymounted coaxially around the male connector body and positioned by astop ring 77 to the rear of the key slot. Thus, once the nose of themale body 68 is inserted into the rear of the counterbore 78 in thefemale body 69, rotation of the threaded coupling sleeve 76 will serveto draw the connector bodies longitudinally together until anexternally-enlarged shoulder 79 on the threaded sleeve is firmly clampedbetween an enlarged shoulder 80 on the male connector body and the endof the female connector body.

Since there must be an electrical connection between the gun-actuatingmeans 27 and the detonator 36, it is preferred to also employ thetubular mandrels, as at 65 and 66, as conduits for carrying serialsections of a single wire, as at 81 and 82, leading to the perforatinggun 29. The body of the gun 29 will, of course, serve as an electricalreturn. Accordingly, the adjacent ends of the wire sections 81 and 82are connected to a set of typical male and female electrical connectors,as at 83 and 84, which are respectively arranged in the mandrelconnector bodies 68 and 69. Since it is preferred to at least minimizeshifting of the electrical connectors 83 and 84, tubular sockets, as at85 and 86, are coaxially arranged within each end of the mandrelconnector bodies 68 and 69 and complementally shaped for respectivelysupporting at least the rear portions of the electrical connectors. As afurther precaution, the electrical wires 81 and 82 may also be retainedin place by providing insulating sleeves, as at 87 and 88, which arepositioned so as to be respectively clamped by the set screws 72 and 73.It will, of course, be recognized that by virtue of the sockets 85 and86, the electrical connectors 83 and 84 will be retained in an alignedposition so as to be simultaneously coupled as the mandrel connectorbodies 68 and 69 are drawn together by rotation of the coupling sleeve76.

It will be recognized, therefore, that the asssembly of the perforatingapparatus can be readily accomplished on a sequential basis. Thus, forexample, a selected number of the charge-supporting strips, as at 38 and39, with shaped charges, as at 41 and 42, arranged thereon can beinserted into the surface end of a selected conduit in the productionsystem 11 and progressively moved into the conduit as a selected numberof the extension mandrels,, as at 65 and 66, are added to continue theprogressive assembly of the perforating apparatus 10. Once the uppermostone of the extension mandrels, as at 65, is coupled to the next-highestmandrel, as at 66, the upper end of the uppermost mandrel is secured tothe lower end of the housing 35 so as to position the mandrels in aselected angular orientation in relation to that housing. Since it is,of course, known that the charge-supporting strips, as at 38 and 39, aresecured in a known orientation relative to each of the mandrels 65 and66, it will be similarly assured that the shaped charges, as at 41 and42, will be in a known angular relationship to the gunpositioninghousing 35. The remainder of the perforating apparatus 10 is assembledand then moved into the production system 11 for being selectivelydispatched into the sub-sea well bore 12.

As the assembled perforating apparatus 10 traverses a first bend (notshown) in the production system 11 which requires articulation of anytwo adjacent chargesupporting strips, as at 38 and 39, in theaforementioned first plane of rotational movement (shown in FIG. 2),there will, of course, be little, if any, restraint of the relativemovements of the strips in the directions shown by the arrows 55. ltwill be recognized that the bolt 49 will simply serve as a pivot in thissituation. On the other hand, assume that the perforating apparatus 10is navigating a second bend (not shown) in the production system 11which lies at right angles to the aforementioned first bend. As adjacentchargesupporting strips, as at 38 and 39, are moved through this secondbend, they will have to move relative to one another in theaforementioned second plane of rotational movement (as represented bythe arrows 60 in FIG. 3). This relative movement is, of course,accomplished by virtue of the large annular clearance space between thebolt 49 and the sides of the holes 51 and 52 in the strip end portions45 and 46, respectively, and the relatively-short longitudinal spacingbetween the rounded noses 58 and 59 of the end portions and the edges ofthe holes.

As mentioned previously, turning in this second plane of movement isfacilitated since the grommet 53 will yield as necessary to allow theextreme end or transverse edge of the rounded nose, as at 58, of onestrip end portion 45 to roll in relation to the other end portion 46 asthe strips 38 and 39 turn out of coincidental alignment with one anotheras necessary to navigate a bend in the production system 11. It will,however, be recognized that the relatively-wide widths of the strips,

as at 38 and 39, will preclude twisting or turning of one strip inrelation to the other about their longitudinal axes. As previouslydiscussed, therefore, it will be well assured that one strip, as at 38,cannot twist relative to the other strip 39.

Moreover, the grommet 53 will cooperate to resiliently bias the opposedsurfaces of the end portions 45 and 46 together. Thus, it will be knownas a certainty that once the perforating apparatus 10 is seated in thelanding nipple 24 and has been properly oriented by the cooperation ofthe gun-positioning means 28 therewith, all of the severalcharge-supporting strips, as at 35 and 36, will be longitudinallyaligned in a predetermined common elongated plane as detined by thefaces of the strips. This will, of course, mean that the several shapedcharges, as at 41 and 42, will be selectively directed so as to avoiddamaging the adjacent piping string 23 upon actuation of the detonator36.

As the perforating apparatus 10 moves through the production system 11,it will, of course, be recognized that the several extension members, asat 65 and 66, of the perforating gun 29 will also have to bend asnecessary to navigate the several bends in the system. However, aspreviously mentioned, the several smalldiameter extension mandrels 65and 66 are all of sufficient resilience that they can momentarily flexas necessary and then return to their original straight configurationafter passing a bend in the production system 11. Since the extensionmembers 65 and 66 are all keyed together, it will, of course, be assuredthat the perforating gun 29 will have remained in its initialpredetermined angular orientation in relation to the gunpositioninghousing 35 once the housing is seated in the landing nipple 24.

Accordingly, it will be appreciated that the present invention hasprovided new and improved perforating apparatus 10 which is speciallyarranged for operation in remote sub-sea wells that are communicated tothe surface by means of many short-radius bends which are closely spacedfrom one another. By virtue of the unique coupling means employed withthe perforating apparatus of the present invention, it will be knownthat the several shaped charges carried by the peforating apparatus willalways be safely directed to avoid damaging an adjacent string of wellpiping once the perforating apparatus is seated in a correctlypositionedlanding nipple in the pipe string carrying the perforating apparatus.

While only a particular embodiment of the present invention has beenshown and described, it is apparent that changes and modifications maybe made without departing from this invention in its broader aspects;and, therefore, the aim in the appended claims is to cover all suchchanges and modifications as fall within the true spirit and scope ofthis invention.

What is claimed is:

1. Perforating apparatus adapted for movement through multi-curvedconduits between the surface and a selected position in a well bore andcomprising:

a plurality of elongated members including at least two members thereofrespectivelyarranged for carrying at least one shaped explosive chargesand including similar tongue-like coengageable terminal portions on saidtwo members with generallyplanar opposed surfaces bounded by thelongitudinal edges thereof extending to their respective outermost endsand each having a hole located about midway between its said edges andlongitudinally spaced from its said end by a predetermined distancewhich is less than the spacing between said hole and either of saidedges;

a pivot member mounted in said holes for intercoupling said terminalportions of said two members and defining a first pivotal axis generallyperpen dicular to said opposed surfaces, said pivot member being sizedsufficiently smaller than said holes for allowing said end of either ofsaid terminal portions to roll on the said opposed surface of the otherof said terminal portions about a second pivotal axis extendinggenerally at right angles to said first pivotal axis; and

biasing means mounted between said pivot member and one of said terminalportions for normally urging said opposed surfaces into slidablecoengagement as said two members pivot about said first pivotal axis andcooperatively arranged for yielding to allow said opposed surfaces todiverge as said two members pivot about said second pivotal axis.

2. The perforating apparatus of claim 1 wherein said two members aregenerally-rectangular, substantiallyrigid strips respectively coupled tosaid terminal portions and having at least one opening therein adaptedfor receiving a shaped explosive charge.

3. The perforating apparatus of claim 1 wherein said two members aregenerally-rectangular, substantiallyrigid strips respectively having atleast one opening therein adapted for receiving a shaped explosivecharge, said terminal portions being the integral end portions of saidstrips.

4. The perforating apparatus of claim 1 wherein said two members aregenerally-rectangular metal strips respectively having at least oneopening therein adapted for receiving a shaped explosive charge, othersof said elongated members are substantially-flexible metal tubes, andfurther comprising:

coupling means cooperatively arranged for tandemly intercoupling saidtubes to one of said strips as well as to one another and includingfirst and second coengageable coupling members on the adjoining ends ofeach of said tubes, and means including a longitudinal slot on one ofsaid coupling members and a lateral key on the other of said couplingmembers adapted for complementary reception in said slot forco-rotatively intercoupling said tubes into a predetermined angularalignment relative to one another and to said strips.

5. Perforating apparatus adapted for movement through multi-curvedconduits between the surface and a selected position in a well bore andcomprising:

a plurality of elongated metal strips, each of said strips respectivelyhaving at least one enlarged opening in an intermediate portion thereoffor cooperatively supporting a shaped explosive charge and a reducedopening centrally located in at least one terminal portion thereof andlongitudinally spaced away from its transverse end by a predetermineddistance which is less than half of its lateral width; and

a plurality of biaxially-pivotal coupling means cooperatively arrangedfor tandemly intercoupling the overlapped terminal portions of eachintercoupled set of said strips, each of said coupling means including apivot member in said reduced openings for defining a first pivotal axis,said pivot member being sized sufficiently smaller than said reducedopenings for allowing said transverse end of either of said overlappedterminal portions to roll on the opposing surface of the other of saidoverlapped terminal portions about a second pivotal axis extendinggenerally at right angles to said first pivotal axis, and biasing meansmounted between said pivot member and one of said overlapped terminalportions normally urging said opposing surfaces into slidablecoengagement as said intercoupled strips pivot about said first pivotalaxis and cooperatively arranged for yielding to allow said opposingsurfaces to diverge as said intercoupled strips pivot about said secondpivotal axis.

6. The perforating apparatus of claim 5 wherein said terminal portionsare respectively offset in relation to said intermediate portions ofsaid strips for locating said opposing surfaces in a plane substantiallyparallel to and between the planes respectively defined by the forwardand rearward faces of said intermediate strip portions.

7. The perforating apparatus of claim 5 further including:

a plurality of substantially-flexible metal tubes; and

tube-coupling means cooperatively arranged for tandemly intercouplingsaid tubes to one of said strips and to one another and including firstand second coengageable tube-coupling members on the adjoining ends ofeach of said tubes, and means including a longitudinal slot on one ofsaid tubecoupling members and a lateral key on the other of saidtube-coupling members adapted for reception in said slot forco-rotatively intercupling said tubes into a predetermined angularalignment relative to one another and to said strips.

8. The perforating apparatus of claim 5 wherein the outermost part ofeach of said terminal portions is curved outwardly from the planerespectively defined by said opposing surface of said terminal portionfor providing a rolling surface adjacent to its said transverse end.

9. The perforating apparatus of claim 8 wherein each of said terminalportions is offset in relation to its adjacent intermediate portion soas to position its said opposing surface in a plane generally parallelto and between the planes respectively defined by the forward andrearward surfaces of said adjacent intermediate portion.

10. The perforating apparatus of claim 9 wherein said outermost part ofeach of said terminal portions also has its corners removed so as toreduce said transverse end to a dimension less than said lateral width.

11. Perforating apparatus adapted for movement through multi-curvedconduits between the surface and a selected position in a well bore andcomprising:

perforating means including a plurality of shaped explosive charges anddetonating means cooperatively arranged for selectively detonating saidshaped charges;

means for supporting said shaped charges for movement to a selectedposition in a well bore and including a plurality of elongated metalstrips, each strip respectively having at least one enlarged opening inan intermediate portion thereof for cooperatively supporting one of saidshaped charges and a reduced opening centrally located in at least oneterminal portion of each of said strips and longitudinally spaced awayfrom the transverse end thereof by a predetermined distance which isless than half of the lateral width of said terminal portion;

a plurality of biaxially-pivotal coupling means cooperatively arrangedfor tandemly intercoupling successive ones of said strips, each of saidcoupling means including a pivot member mounted through the reducedopenings in the coengaged terminal portions of at least a first andsecond one of said strips for defining a first pivotal axis, said pivotmember being sized sufficiently smaller than said reduced openings forallowing said transverse end of either of said coengaged terminalportions to roll on the opposing surface of the other of said coengagedterminal portions about a second pivotal axis extending generally atright angles to said first pivotal axis, and biasing means mountedbetween said pivot member and one of said coengaged terminal portionsnormally urging said opposing surfaces into slidable coengagement assaid first and second strips pivot about said first pivotal axis andcooperatively arranged for yielding to allow said opposing surfaces todiverge as said first and second strips pivot about said second pivotalaxis;

tool-propelling means adapted for movement through such conduits inresponse to selected pressure changes in such conduits; and

means tandemly intercoupling said tool-propelling means to said firstand second strips.

12. The perforating apparatus of claim 11 wherein said coengagedterminal portions are respectively offset in relation to saidintermediate portions of said first and second strips for locating saidopposing surfaces in a plane parallel to and between the planesrespectively defined by the forward and rearward faces of saidintermediate portions of said first and second strips.

13. The perforating apparatus of claim 11 wherein said means tandemlyintercoupling said tool-propelling means to said strips include:

a plurality of substantially-flexible metal tubes;

tube-coupling means cooperatively arranged for tandemly intercouplingsaid tubes to one of said strips and to one another and including firstand second conengageable tube-coupling members on the adjoining ends ofeach of said tubes, and means including a longitudinal slot on one ofsaid tubecoupling members and a lateral key on the other of saidtube-coupling members adapted for reception in said slot forco-rotatively intercoupling said tubes into a predetermined angularalignment relative to one another and to said strips.

14. The perforating apparatus of claim 11 wherein the outermost part ofeach of said coengaged terminal portions is turned outwardly from theplane respectively defined by its said opposing surface for providing arolling surface adjacent to its said transverse end.

15. The perforating apparatus of claim 14 wherein each of said coengagedterminal portions is offset in relation to its adjacent intermediateportion so as to position its said opposing surface in a plane lyingparallel to and between the planes respectively defined by the forwardand rearward surfaces of its adjacent intermediate portion.

16. The perforating apparatus of claim 15 wherein said outermost part ofeach of said terminal portions also has its corners removed so as toreduce said transverse end to a dimension less than said lateral width.

17. The perforating apparatus of claim 11 further including:

tooLpositioning means cooperatively arranged between saidtool-propelling means and said strips for selectively orienting saidstrips into a predetermined angular position upon movement of saidperforating apparatus to said selected well bore position.

18. The perforating apparatus of claim 17 further including:

means cooperatively coupled to said detonating means for selectivelydisarming said detonating means at least until said strips are in theirsaid predetermined angular position.

19. The perforating apparatus of claim 18 wherein said means tandemlyintercoupling said tool-propelling means to said strips include:

a plurality of substantially-flexible metal tubes;

tube-coupling means cooperatively arranged for tandemly intercouplingsaid tubes to one of said strips and to one another and including firstand second coengageable tube-coupling members on the adjoining ends ofeach of said tubes, and means including a longitudinal slot on one ofsaid tubecoupling members and a lateral key on the other of saidtube-coupling members adapted for reception in said slot forco-rotatively securing said tubes in a predetermined angular alignmentrelative to one another and to said strips.

1. Perforating apparatus adapted for movement through multi-curvedconduits between the surface and a selected position in a well bore andcomprising: a plurality of elongated members including at least twomembers thereof respectively arranged for carrying at least one shapedexplosive charges And including similar tongue-like coengageableterminal portions on said two members with generally-planar opposedsurfaces bounded by the longitudinal edges thereof extending to theirrespective outermost ends and each having a hole located about midwaybetween its said edges and longitudinally spaced from its said end by apredetermined distance which is less than the spacing between said holeand either of said edges; a pivot member mounted in said holes forintercoupling said terminal portions of said two members and defining afirst pivotal axis generally perpendicular to said opposed surfaces,said pivot member being sized sufficiently smaller than said holes forallowing said end of either of said terminal portions to roll on thesaid opposed surface of the other of said terminal portions about asecond pivotal axis extending generally at right angles to said firstpivotal axis; and biasing means mounted between said pivot member andone of said terminal portions for normally urging said opposed surfacesinto slidable coengagement as said two members pivot about said firstpivotal axis and cooperatively arranged for yielding to allow saidopposed surfaces to diverge as said two members pivot about said secondpivotal axis.
 2. The perforating apparatus of claim 1 wherein said twomembers are generally-rectangular, substantially-rigid stripsrespectively coupled to said terminal portions and having at least oneopening therein adapted for receiving a shaped explosive charge.
 3. Theperforating apparatus of claim 1 wherein said two members aregenerally-rectangular, substantially-rigid strips respectively having atleast one opening therein adapted for receiving a shaped explosivecharge, said terminal portions being the integral end portions of saidstrips.
 4. The perforating apparatus of claim 1 wherein said two membersare generally-rectangular metal strips respectively having at least oneopening therein adapted for receiving a shaped explosive charge, othersof said elongated members are substantially-flexible metal tubes, andfurther comprising: coupling means cooperatively arranged for tandemlyintercoupling said tubes to one of said strips as well as to one anotherand including first and second coengageable coupling members on theadjoining ends of each of said tubes, and means including a longitudinalslot on one of said coupling members and a lateral key on the other ofsaid coupling members adapted for complementary reception in said slotfor co-rotatively intercoupling said tubes into a predetermined angularalignment relative to one another and to said strips.
 5. Perforatingapparatus adapted for movement through multicurved conduits between thesurface and a selected position in a well bore and comprising: aplurality of elongated metal strips, each of said strips respectivelyhaving at least one enlarged opening in an intermediate portion thereoffor cooperatively supporting a shaped explosive charge and a reducedopening centrally located in at least one terminal portion thereof andlongitudinally spaced away from its transverse end by a predetermineddistance which is less than half of its lateral width; and a pluralityof biaxially-pivotal coupling means co-operatively arranged for tandemlyintercoupling the overlapped terminal portions of each intercoupled setof said strips, each of said coupling means including a pivot member insaid reduced openings for defining a first pivotal axis, said pivotmember being sized sufficiently smaller than said reduced openings forallowing said transverse end of either of said overlapped terminalportions to roll on the opposing surface of the other of said overlappedterminal portions about a second pivotal axis extending generally atright angles to said first pivotal axis, and biasing means mountedbetween said pivot member and one of said overlapped terminal portionsnormally urging said opposing surfaces into slidable coengagement assaid intercoupled strips pivot about said firsT pivotal axis andcooperatively arranged for yielding to allow said opposing surfaces todiverge as said intercoupled strips pivot about said second pivotalaxis.
 6. The perforating apparatus of claim 5 wherein said terminalportions are respectively offset in relation to said intermediateportions of said strips for locating said opposing surfaces in a planesubstantially parallel to and between the planes respectively defined bythe forward and rearward faces of said intermediate strip portions. 7.The perforating apparatus of claim 5 further including: a plurality ofsubstantially-flexible metal tubes; and tube-coupling meanscooperatively arranged for tandemly intercoupling said tubes to one ofsaid strips and to one another and including first and secondcoengageable tube-coupling members on the adjoining ends of each of saidtubes, and means including a longitudinal slot on one of saidtube-coupling members and a lateral key on the other of saidtube-coupling members adapted for reception in said slot forco-rotatively intercupling said tubes into a predetermined angularalignment relative to one another and to said strips.
 8. The perforatingapparatus of claim 5 wherein the outermost part of each of said terminalportions is curved outwardly from the plane respectively defined by saidopposing surface of said terminal portion for providing a rollingsurface adjacent to its said transverse end.
 9. The perforatingapparatus of claim 8 wherein each of said terminal portions is offset inrelation to its adjacent intermediate portion so as to position its saidopposing surface in a plane generally parallel to and between the planesrespectively defined by the forward and rearward surfaces of saidadjacent intermediate portion.
 10. The perforating apparatus of claim 9wherein said outermost part of each of said terminal portions also hasits corners removed so as to reduce said transverse end to a dimensionless than said lateral width.
 11. Perforating apparatus adapted formovement through multi-curved conduits between the surface and aselected position in a well bore and comprising: perforating meansincluding a plurality of shaped explosive charges and detonating meanscooperatively arranged for selectively detonating said shaped charges;means for supporting said shaped charges for movement to a selectedposition in a well bore and including a plurality of elongated metalstrips, each strip respectively having at least one enlarged opening inan intermediate portion thereof for cooperatively supporting one of saidshaped charges and a reduced opening centrally located in at least oneterminal portion of each of said strips and longitudinally spaced awayfrom the transverse end thereof by a predetermined distance which isless than half of the lateral width of said terminal portion; aplurality of biaxially-pivotal coupling means cooperatively arranged fortandemly intercoupling successive ones of said strips, each of saidcoupling means including a pivot member mounted through the reducedopenings in the coengaged terminal portions of at least a first andsecond one of said strips for defining a first pivotal axis, said pivotmember being sized sufficiently smaller than said reduced openings forallowing said transverse end of either of said coengaged terminalportions to roll on the opposing surface of the other of said coengagedterminal portions about a second pivotal axis extending generally atright angles to said first pivotal axis, and biasing means mountedbetween said pivot member and one of said coengaged terminal portionsnormally urging said opposing surfaces into slidable coengagement assaid first and second strips pivot about said first pivotal axis andcooperatively arranged for yielding to allow said opposing surfaces todiverge as said first and second strips pivot about said second pivotalaxis; tool-propelling means adapted for movement through such conduitsin response to selected pressure chAnges in such conduits; and meanstandemly intercoupling said tool-propelling means to said first andsecond strips.
 12. The perforating apparatus of claim 11 wherein saidcoengaged terminal portions are respectively offset in relation to saidintermediate portions of said first and second strips for locating saidopposing surfaces in a plane parallel to and between the planesrespectively defined by the forward and rearward faces of saidintermediate portions of said first and second strips.
 13. Theperforating apparatus of claim 11 wherein said means tandemlyintercoupling said tool-propelling means to said strips include: aplurality of substantially-flexible metal tubes; tube-coupling meanscooperatively arranged for tandemly intercoupling said tubes to one ofsaid strips and to one another and including first and secondconengageable tube-coupling members on the adjoining ends of each ofsaid tubes, and means including a longitudinal slot on one of saidtube-coupling members and a lateral key on the other of saidtube-coupling members adapted for reception in said slot forco-rotatively intercoupling said tubes into a predetermined angularalignment relative to one another and to said strips.
 14. Theperforating apparatus of claim 11 wherein the outermost part of each ofsaid coengaged terminal portions is turned outwardly from the planerespectively defined by its said opposing surface for providing arolling surface adjacent to its said transverse end.
 15. The perforatingapparatus of claim 14 wherein each of said coengaged terminal portionsis offset in relation to its adjacent intermediate portion so as toposition its said opposing surface in a plane lying parallel to andbetween the planes respectively defined by the forward and rearwardsurfaces of its adjacent intermediate portion.
 16. The perforatingapparatus of claim 15 wherein said outermost part of each of saidterminal portions also has its corners removed so as to reduce saidtransverse end to a dimension less than said lateral width.
 17. Theperforating apparatus of claim 11 further including: tool-positioningmeans cooperatively arranged between said tool-propelling means and saidstrips for selectively orienting said strips into a predeterminedangular position upon movement of said perforating apparatus to saidselected well bore position.
 18. The perforating apparatus of claim 17further including: means cooperatively coupled to said detonating meansfor selectively disarming said detonating means at least until saidstrips are in their said predetermined angular position.
 19. Theperforating apparatus of claim 18 wherein said means tandemlyintercoupling said tool-propelling means to said strips include: aplurality of substantially-flexible metal tubes; tube-coupling meanscooperatively arranged for tandemly intercoupling said tubes to one ofsaid strips and to one another and including first and secondcoengageable tube-coupling members on the adjoining ends of each of saidtubes, and means including a longitudinal slot on one of saidtube-coupling members and a lateral key on the other of saidtube-coupling members adapted for reception in said slot forco-rotatively securing said tubes in a predetermined angular alignmentrelative to one another and to said strips.